1. Field of the Invention
The present invention relates to an operating device having a plurality of steering wheel switches provided on a steering wheel.
2. Description of the Related Art
Vehicle-mounted equipment operating switches called “steering wheel switches” are well known in the art. These switches are provided on a spoke portion of a steering wheel so that a driver holding the steering wheel can operate them with the thumb, thereby enabling the driver to conduct various operations for the vehicle-mounted equipment without having to remove his or her hands from the steering wheel while a motor vehicle is moving.
As one example of this kind of operating device, there is conventionally known a vehicle-mounted display device that includes an operation input device having a plurality of operating parts arranged on a steering wheel in the passenger compartment, a display unit for displaying various kinds of information, an option menu database storage device for storing an option menu database inclusive of option menu information regarding a list of processing commands according to the operation of the respective operating parts of the operation input device, and a display control unit responsive to the operation of the operating parts of the operation input means for reading out the option menu database stored in the option menu database storage device to allot the processing commands included in an option menu to the respective operating parts and for causing the display device to display the corresponding relationship between the processing commands included in the option menu and the respective operating parts (See, e.g., Japanese Patent Application Publication No. JP-A-2003-131791).
In addition, a vehicle-mounted equipment operating system in which an electrode for sensing the contact of the driver's thumb with steering wheel switches is provided in order for a driver to visually recognize the positions and kinds of the switches without turning his or her eyes from the front of a vehicle (a distant view field) to a steering wheel (a nearby view field) to operate the switches. If the contact is sensed, individual operation items corresponding to the respective steering wheel switches are displayed on a head-up display and the operation item associated with the currently touched switch is highlighted as by reversed display, thereby informing the driver of the operation item corresponding to the position of his or her thumb with no need for the driver to directly look at the steering wheel switches (See, e.g., Japanese Patent Application Publication No. JP-A-2003-175783).
However, the arrangement disclosed in Japanese Patent Application Publication No. JP-A-2003-131791 is inconvenient to use, because it is necessary for the driver to judge the size of the switch by touch, or operate the switch on a trial basis, or look at the switch, in order to make determination as to which steering wheel switch is currently touched by the thumb. On the other hand, with the arrangement taught in Japanese Patent Application Publication No. JP-A-2003-175783, the driver can discriminate the steering wheel switch currently touched by the thumb without having to directly look at the switch. Without the looking directly at the steering wheel, however, it is impossible for the driver to learn the current positional relationship between the thumb and the rest of the steering wheel switches. For this reason, when the driver wishes to operate other steering wheel switches than the one currently touched by the thumb, there is a need for the driver to directly look at the layout of the steering wheel switches. This inconveniences the driver.